Moisturizers are usually applied directly to the skin as leave-on products. Personal cleansing products are usually applied with water as a foam or lather and rinsed off with clear water. Ideal rinse off personal cleansers should cleanse the skin gently, causing little or no irritation without defatting and or drying the skin and without leaving skin taut after frequent use. Most lathering personal cleansing products, bar soaps, liquids and syndet liquids fail in this respect.
Some current commercial personal cleansing liquids claim to "moisturize" the skin. But, most of these current cleansing liquid products do not deliver an adequate moisturizing benefit. Therefore, users typically must moisturize their skin with a separate leave-on product following cleansing.
It would be highly desirable to improve the delivery of skin moisturizers from a cleansing liquid composition over the current commercial personal cleansing liquids. If this were accomplished it would provide users with the convenience of obtaining both a cleansing and a moisturizing benefit from a single product.
Dual cleansing and lipid moisturizing liquid compositions are very difficult to formulate and process. One reason is the cleansing ingredients, in general, tend to be incompatible with the lipid moisturizing ingredients. Another problem is processing on a commercial scale. Yet another problem is getting the lipid in the liquid to deposit on the skin of the user. The deposition of lipid moisturizer from the liquid, onto the skin can be very low due to loss of the lipid in the wash and the rinse. Conversely, it can feel too sticky if deposited on the skin. Still another problem is formulating a dual liquid that lathers well. Another problem is formulating a dual liquid that is storage stability. Yet another problem is formulating a dual liquid that is stress stable.
The actual deposition of lipid moisturizer from a lathering dual liquid composition is essential for effective lipid benefit. No known commercial prior art liquid that claims to be a cleansing and lipid moisturizing liquid, deposits as much 3 micrograms of lipid moisturizer per cm. sq. of washed skin.
U.S Pat. No. 3,829,563, Barry et al., issued Aug. 13, 1974, discloses an emollient cleansing liquid and paste composition containing 10-70 parts by weight petrolatum with up to 98 parts, preferably, 95-98 parts, having a diameter particle size smaller than 5 microns.
U.S. Pat. No. 5,308,526, Dias et. al., issued May 3, 1994, incorporated herein by reference, discloses liquid skin compositions with up to 5 parts petrolatum wherein 20-80 parts of said petrolatum particles have a particle size from 10-120 microns.
U.S. Pat. No. 5,312,559, Kacher et al., issued May 17, 1994, incorporated herein by reference, discloses semi-solid compositions of 60,000 to 400,00 cps containing 0.5 parts to 15 parts petrolatum having a particle size distribution in which 20% to 80% of the particles are 10-120 microns.
Shelf stable dual skin cleansing liquid composition, as defined herein, are stable for at least two weeks at room temperature. However, such composition are not required to be stable under stress conditions, as defined below herein.
Therefore, it is an object of the present invention to provide an effective, yet gentle, dual skin cleansing liquid composition which is stress stable.
It is an aspect of the present invention to provide an effective, yet gentle, dual skin cleansing liquid composition which actually deposit enough lipid on the skin to provide superior skin moisturizing and sensory benefits while maintaining its lathering and cleaning properties.
In addition to the acute skin moisturizing and sensory benefits mentioned above, another aspect of the present invention is to provide improved skin moisturization and conditioning benefits over time through the continued or chronic use of the skin cleansing liquid composition of the present invention.